Home
SearchSearch MemberlistMemberlist RegisterRegister ProfileProfile Log in to check your private messagesLog in to check your private messages Log inLog in

Basic techniques to repair lenses (and cameras)
View previous topic :: View next topic  


PostPosted: Tue May 21, 2019 1:59 pm    Post subject: Reply with quote

DConvert, Adding my personal garage level experience with over the counter solvents... Hopefully it will compliment your lab experience.

I can confirm that hardware store naptha does soften vinyl work mats and may remove lens element paint. It also evaporates somewhat slower and cuts through oil (tar and grease) nicely.

When cleaning the entire surface of an assembled lens I try to avoid any solvents that evaporate super fast like denatured alcohol or iso-propyl 90%. I only use those solvents when the element is open and separate from the lens housing.

What I have noticed is that the rapid evaporation is causing cooling of the element, which may draw condensation into the backside group or housing.

The most critical personally; Decreased work time because of rapid evaporation may find yourself with no solvent to float the oils while wiping.

Adding a slower evap solvent like Zeiss lens cleaner after applying a rapid evaporating solvent can help with post cleanup of oils without the possibility of ending up with a dry scratchy texwipe, pecpad, cotton swab or kimwipe.

Also note that there is a good chance that many solvents will require the side of an element to be re-painted black.


Like 1 small


PostPosted: Wed May 22, 2019 8:29 am    Post subject: Reply with quote

Blazer0ne wrote:
DConvert, Adding my personal garage level experience with over the counter solvents... Hopefully it will compliment your lab experience.

I can confirm that hardware store naptha does soften vinyl work mats and may remove lens element paint. It also evaporates somewhat slower and cuts through oil (tar and grease) nicely.

When cleaning the entire surface of an assembled lens I try to avoid any solvents that evaporate super fast like denatured alcohol or iso-propyl 90%. I only use those solvents when the element is open and separate from the lens housing.

What I have noticed is that the rapid evaporation is causing cooling of the element, which may draw condensation into the backside group or housing.

The most critical personally; Decreased work time because of rapid evaporation may find yourself with no solvent to float the oils while wiping.

Adding a slower evap solvent like Zeiss lens cleaner after applying a rapid evaporating solvent can help with post cleanup of oils without the possibility of ending up with a dry scratchy texwipe, pecpad, cotton swab or kimwipe.

Also note that there is a good chance that many solvents will require the side of an element to be re-painted black.


Like 1 small


Any hydrocarbon solvent will be likely to do all the things you mentioned. Depending on your desired rate of evaporation gasoline, lighter fluid, white spirit, kerosene, or diesel could all be used (listed in decreasing volatility) the last few will leave residues that don't simply evaporate away.
I'm not sure quite what American 'hardware store naptha' is, but I suspect it's a paint thinner/brush cleaner like our white spirit - a turpentine substitute (sometimes sold under that name at higher prices).

Within each of the volatility ranges there will be a wide range of compositions (I've seen hundreds of different gasolines - some very different from each other) which will cause differences in solvency. A highly paraffinic solvent will have less solvency and so be less likely to remove paint or attack plastics, but will still swell rubber & lift most oils etc. Highly aromatic formulations have better solvency but are more harmful both to you & to plastics etc.

The elements I'm currently working on are proving difficult to get totally clear even using aggressive solvents like acetone, but they are gradually improving - you could barely see through them when I started, now after two tries they've almost reached the point where I wouldn't have felt the need to strip them from the lens i.e. almost good enough that I could make do, certainly not good enough to consider done.


PostPosted: Wed May 22, 2019 9:01 am    Post subject: Reply with quote

Perhaps the best way to avoid or minimize scrubbing of highly contaminated surface is the same as with anything else: give it a proper soak.
By proper, I mean several days of it.

I wouldn't do this to a group though.
Whether it looks glued or not, there is a chance of getting solvent inside, and that would create a bigger problem than the initial haze was.


PostPosted: Wed May 22, 2019 9:23 am    Post subject: Reply with quote

I use the naphtha that's available at the big box stores -- dunno specifically what it is, although I guess the fine print on the can will tell me. I've used it for years, however, without harmful effects. I also use naphtha when finishing guitars. I use a method known as "french polish" where naphtha is lightly mixed with the shellac as a means of extending it before it becomes tacky. But that's a whole different world from cameras.

As for iso-proponal, I wish I could find 100%, the best I've been able to find is 70%. I find that denatured alcohol is a more powerful solvent anyway, but I suspect that one should use it with caution because I know it can damage finishes, so it might also be a bit too agressive with some plastics. But it is a great solvent, and is also a main ingredient in the "french polish" process, which is why I always keep some around.


PostPosted: Wed May 22, 2019 10:54 am    Post subject: Reply with quote

Amazon has everything.